Microsoft Access - PA Harris, Vanderbilt University A Primer for Relational Database Design and Use Paul A. Harris, Ph.D. Director, GCRC Informatics October. - презентация

1 Microsoft Access - PA Harris, Vanderbilt University A Primer for Relational Database Design and Use Paul A. Harris, Ph.D. Director, GCRC Informatics October 3, 2003

2 Microsoft Access – Module 1 PA Harris, Vanderbilt University An Overview of MS-Access

3 What is Microsoft Access? Microsoft Access is a relational database management system (DBMS or RDBMS). At the very core, it is a software engine that provides an interface between physical data and user application queries. Other examples of DBMS applications include: Oracle mySQL SQL Server (Microsoft) DB2 (IBM) Informix PA Harris, Vanderbilt University

4 Why choose MS-Access over SPSS / Excel? Although there is always overlap, the following rules might help when deciding when / when not to use MS Access: MS Access is best used for long-term data storage and/or data sharing. MS Excel is best used for minor data collection, manipulation, and especially visualization. SPSS is best used for minor data collection and especially data analysis. It is easy to export data from MS Access to Excel SPSS PA Harris, Vanderbilt University

5 Why choose MS-Access over other DBMS systems? Cheap, readily available (packaged with MS-Office Premium). Easy to use (relative to other systems –Oracle may require one FTE to maintain the server as a database administrator and another FTE to serve as an application developer). Includes front-end tools for rapid application development (RAD). This also makes MS-Access a good prototype environment. PA Harris, Vanderbilt University

6 Why choose other DBMS systems over MS-Access? MS-Access can handle a large number of records, but is somewhat slow compared to some of the high-end platforms. Multiple users may use the database simultaneously, but MS- Access is known to become unstable with greater than 3-5 users. There is a snob factor. I personally recommend the use of other systems (Oracle, SQL Server, mySQL, etc) when writing grant proposals - especially phase II type grants). PA Harris, Vanderbilt University

7 What is in an MS-Access file - 1? Although the term database typically refers to a collection of related data tables, an Access database includes more than just data. In addition to tables, you can add: Saved queries (stored procedures) - organizing and/or manipulating data Forms – gui interaction with data, event programming Reports – customized results for printing (~ static forms) Macros and VB programs for extending functionality Microsoft provides some logical integration of these tools through wizards. However, these are pretty basic - most developers must pick and choose the best approach when implementing applications. PA Harris, Vanderbilt University

8 What is in an MS-Access file - 2? Unless advanced techniques are employed, all entities are stored in one *.mdb file. When running, a locking file (*.ldb) is also visible. Only the mdb file needs to be copied to transfer the database to another computer or location. Ex. MSCI_ByrneGuestLecture.mdb PA Harris, Vanderbilt University

9 What is in an MS-Access file - 3? DemographicsEthnicityLabsH & P Tables Queries Forms (Active) Reports (Static) VB + Macros – Event Driven Automation, etc. PA Harris, Vanderbilt University

10 Advanced – Splitting PA Harris, Vanderbilt University Back-End File - Contains all Data Tables VB + Macros – Event Driven Automation, etc. DemographicsEthnicityLabsH & P Tables Queries Forms (Active) Reports (Static) Front-End File - Contains all Application Entities (Forms, Queries, etc.) and links to data tables in back-end file. Note you may have more than one FE to accommodate different user types.

11 Microsoft Access – Module 1 Summary PA Harris, Vanderbilt University MS-Access is a powerful relational database program. It has many integrated features and can be greatly customized to fit most personal/departmental needs for data collection and storage.

12 Microsoft Access – Module 2 PA Harris, Vanderbilt University Creating / Working with Tables

13 Tables – Glucose Measurement Database We wish to construct a database to track waking glucose measurements for an indefinite amount of time on 100 patients receiving 3 possible drug combinations. Why would this be difficult in MS-Excel or SPSS? PA Harris, Vanderbilt University

14 Tables Overview Think of Access as a collection of spreadsheets that are relationally linked. STORE DATA ONE TIME / ONE PLACE DO NOT STORE CALCULATED DATA Demographics Patient_ID Fname Lname Address Phone Gender Race DOB Height Glucose Glucose_ID Patient_ID Date Weight Med_ID Glucose Meds Med_ID DrugCombonatio n PA Harris, Vanderbilt University

15 Table Demonstration - Live General Setup for Tables Describe General Options Show Validation Rule Relationships Lookup Option PA Harris, Vanderbilt University

16 Table Relationships - Live Table Relationships Describe Cascade Features PA Harris, Vanderbilt University

17 Table Import / Link - Live Importing a Table makes a copy of existing data Linking a Table lets you control existing data through Access (Exercise Caution !) Note that you may import non-Access files. PA Harris, Vanderbilt University

18 MS Access – Module 2 Summary PA Harris, Vanderbilt University Data storage principles 1.Attempt to store data 1 time / 1 place; 2.Do not store data that may be calculated from other fields (utilize queries); and 3.Strive for very discrete data storage (no ambiguity – garbage in / garbage out). 4.Choose real or arbitrary (autonumber) unique identifier for each record. Relationships Use table relationships to automatically cascade delete and update records. Other Data Sources Import = Copy; Link = Live Connect.

19 Microsoft Access – Module 3 PA Harris, Vanderbilt University Creating / Working with Queries

20 Query Overview - 1 An MS-Access query is a set of stored SQL instructions that manipulate and/or select data from one or more tables. Select Query – Data grouping and/or filtering Make-Table Query – Select + creates/populates new table. Update Query – Updates fields from specified table data Append Query – Runs query on one table, appends results to a table Delete Query – Delete selected records from table PA Harris, Vanderbilt University

21 Query Overview - 2 SQL (Structured Query Language) is a very widely used database language designed specifically for communicating with databases SQL is not proprietary – almost every DBMS supports SQL (including MS-Access). SQL is relatively easy to learn, but extremely powerful – one of the easiest ways to learn is to use MS-Access Query by Example methods, then look at the generated SQL command Remember that a query is nothing more than the database engine running the stored SQL command (it looks and sometimes acts like a table, but really adds little mass to the database file) PA Harris, Vanderbilt University

22 One Table Query Example - Live Right-Click + Add to add table(s) Drag and Drop Fields Custom sort by one or more fields. Use this button to toggle between design, sheet and SQL views. PA Harris, Vanderbilt University

23 2-Table Query Example - Live Drag and Drop Fields Right-Click + Add to add table(s) Note that relationship often automatic. Calculated Field BMI: [Weight]/([Height]/100)^2 Right-Clicking gray area above field enables property changes. PA Harris, Vanderbilt University

24 Query – Calculating Fields Name the calculated field, then type a colon, then type the equation using brackets ( [ ] ) around table fields. If there is ambiguity in the field names between tables, you may need to type table.[field] format. Ex: BMI: [Weight]/([Height]/100)^2 PA Harris, Vanderbilt University

25 Query – Sorting Data Choose Ascending or Descending in the Sort Row This query would sort by Gender THEN by Race. PA Harris, Vanderbilt University

26 Query – Filtering Data This query will return all records in the database for: Females who are not white whose height are greater than 150 cm and who weigh between 60 and 70 kg You need not show the data field to use as a filter. PA Harris, Vanderbilt University

27 Query – Filter Operators = equals > greater than >= greater than or equal < less than <= less than or equal <>not equal to Betweenbetween two values Is Nullfield is empty is not nullfield is not empty LikeMatches a pattern (Like John*) ORLogical OR (one or other is true) ANDLogical AND (both are true) etc. PA Harris, Vanderbilt University

28 Query – Grouping Data - 1 Clicking the Totals Button Enables Grouping, Counting and Statistical Options Notice new Total row. Each field (column) can be set. Running this Query indicates there are 203 Females and 261 Males in the database. PA Harris, Vanderbilt University

29 Query – Grouping Data -2 Totals Options Include: Group By Sum Avg Min Max Count StDev Var PA Harris, Vanderbilt University

30 Query – Export Data Create and Save Query 1) Use OfficeLinks (Excel Toggle Option) to Analyze it with Excel 2) Data Automatically Exported to Excel 3) PA Harris, Vanderbilt University

31 MS Access – Module 3 Summary PA Harris, Vanderbilt University Queries are extremely easy to set up/use and provide an up- to-date snapshot of your data at any time. Queries may be used to calculate values based upon existing fields, join fields from separate tables, globally update or delete data, and export linked/calculated data to external programs. Under the hood, queries are really nothing more than stored SQL statements that are run upon command. They add little mass to the file application. If you use MS-Access for nothing else, you should learn to import data and become proficient with query functionality.

32 MS-Access Import/Query Practice Import data from the sample Excel file msci_data.xls into an Access database table. Design and save a new query named to display only the following fields: 1) Case; 2) Sex; 3) BMI_Av (a calculated field computed by averaging BMI_1 and BMI_2). Select filter criteria in the query to show only those records where: 1) age is between 30 and 90; 2) the sex field equals 0; and 3) and the survdays field contains a value between 100 and 300. Using the imported table from part A, design and save a new query named Question2 to provide summary data for each sex / alive combination (ie we want to see 4 rows of data). For each of these combinations compute: 1) count of case numbers; 2) average of length of stay (LOS); and 3) standard deviation of length of stay (LOS).

33 Microsoft Access – Module 4 PA Harris, Vanderbilt University Creating / Working with Forms/Reports

34 Graphical User Interface (GUI) Although it is possible to enter data directly into a table, you can enhance data quality by forcing data entry through forms. Depending upon your users, you may wish to set things up so they never even see the database window. In other words, you can design your application so they only touch the data through programmed forms. PA Harris, Vanderbilt University

35 Graphical User Interface (GUI) Continuing with the glucose database we formulated earlier, well now attempt to build a graphical user interface to: 1) Collect Data 2) Periodically report data through pre-formatted reports 3) Quit the program PA Harris, Vanderbilt University

36 GUI – Forms/Report Live Out of Program PA Harris, Vanderbilt University

37 MS Access – Module 4 Summary PA Harris, Vanderbilt University Use forms and reports together to build a data software application. Design to the lowest common denominator (Murphy will use your program early and often) Always look for and design carrots to win over the true data entry personnel. If it saves them time or offers something they couldnt do before, they might use the application. Look for champions – bright, energetic individuals who will try something new, etc.

38 MS Access – Resources PA Harris, Vanderbilt University I cannot recommend the BEST MS-Access book. However, I can recommend the following series of books that I usually turn to when learning new technology: Visual Quickstart Series – beginner/intermediate level OReilly Series – intermediate/advanced level There is also an excellent tutorial on the web: